I did a mountain of laundry and came up with a bunch of socks and tees and sweatshirts and long undies that got retired and cut up. Nasty gobs of gunk can get wiped up with those and tossed out.
Then there's a whole 'nother mountain of 'shop towels' washcloths and other small towels that go to the laundromat from time to time. Kinda hope nobody does a load of whites in them four washers anytime soon.
Just an observation but what an awful thing to do to some poor mother of four who is struggling to get by without her own cloths washing equipment and you expose her to possible damage to her children's clothing for rags to clean your toy.
That's right, this is America 2015, we are free to be as awful to each other as we please, my mistake.
Now now there. Don't get your panties in a wad. They charge an extra buck for that. Go back and read the part where the rude stuff goes in the trash. Directly. Laundrymat gets stuff that mostly wouldn't offend the Mrs. too much.
The management had a big ol' list of rules and regulations posted and "Don't wash shop towels!" ain't one of 'em. "Don't wash horse blankets!" is, however, a major concern - big signs everywhere.
Group 3
Those rags that have been in group 2 a few times and are contaminated with oil and to the point that they cause me marital issues if I run them in the washing machine. I use them under motors when I change the oil, when I remove covers etc. I have found that if I keep them in a open weave basket they dry out and can be used for this process many times before I have to dispose of them.
Ever heard of spontaneous combustion? Oily rags belong in a covered metal container.

Hoo boy we're talkin' fancy now.

There's a cute little 8 gallon-ish sized one that's perfect - with no pesky warning labels and such.